First, the capillaries
The wall thickness of the capillary is uniform, and the internal and external surface defects are few. The external surface grinding and internal thread defect cleaning machines and equipment are equipped.
Second, review
Compared with ordinary cold drawn seamless steel tubes, the production and manufacturing of cold drawn seamless steel tubes has improved the pickling re inspection process of hot rolled capillary tubes. The key is to ensure that the outer surface of the capillary tubes is free of defects such as expansion and cracks, and remove the capillary tubes with defects such as expansion, relatively serious line drawing, and surface.
The third is special tools
Generally, the surface smoothness of special tools commonly used in the production and manufacture of cold drawn seamless steel pipes is specified above Ra0.4, the specification precision is specified above H3, and the strength is specified above HRC70. In addition, it is stipulated that the steel adhesion on the top or die shell is not allowed during the whole process of drawing.
The fourth is quenching
Quenching is a very critical process in the production and manufacturing of all cold drawn pipes. The quality of quenching harms the characteristics of seamless steel pipes and the removal of zinc ash. Cold drawn precision seamless steel pipe must be equipped with airless oxidation quenching furnace machinery and equipment.
Finally, pickling
In the whole process of hydrochloric acid pickling, the cold drawn seamless steel pipe is easy to produce black slag dominated by Fe2O3 and Fe3O4, which will cause black spots on the surface in the subsequent production process. Fe2O3 and Fe3O4 are dissolved in sulfuric acid. To better avoid the generation of black spots, 5-20g/l of Na is added to the acid tank.
